

Vol. XLI. GUELPH, JANUARY, 1909. No. 1. 



PRACTICAL AND POPULAR ENTOMOLOGY.— No. 26. 



The Preparation of Beetles for the Microscope, 

 by h. f. wickham, iowa city, iowa. 



Twenty-five years ago the use of the compound microscope in the 

 study of beetles was comparatively uncommon, nearly all collectors being 

 satisfied to do what they could with a hand lens and to take the rest on 

 trust, sending the majority of their smaller captures to some "authority" 

 whose word must necessarily be law. There is now a decided and grow- 

 ing tendency in America to break away from the traditional method of 

 obtaining names, and this feeling is reflected in several letters received 

 from correspondents asking information on matters of technic. The 

 accompanying notes are offered as an outline which may be followed at 

 light expense by any one who has access to a microscope, and while no 

 originality is claimed for the processes, they are presented in this form in 

 hope that they may benefit some student who has not the privilege of 

 studying under professional supervision, and who is without manuals on 

 microscopical methods. While capable of extension and modification in 

 many directions, the plan here outlined suffices for all ordinary study of 

 external structures so far as they concern the present-day classification of 

 Coleoptera. Larvte may be prepared in the same way. 



Such structures as those pertaining to the sclerites of the ventral 

 surface, the main points of sculpture and vestiture, the insertion and 

 general form of the antennae, and even the shape and armature of the 

 mentum may be made out with comparatively little difficulty in all but the 

 smallest beetles by any one who has a good hand lens and who will take 

 pains to compare these structures as illustrated by a kw identified forms 

 with those he desires to investigate. In other words, progress should be 

 from the known to the unknown rather than the taking up of the latter as 

 a distinct proposition. Ordinarily the parts requiring investigation under 

 high power are the legs and antennae of small species, with the aim of 

 determining accurately the number and proportions of the joints, the 

 extent of anchylosis, and so on ; the mouth-parts of even the larger 



